The pilot reported that after a series of uneventful touch-and-go landings in the tailwheel-equipped airplane, he decided to perform a full stop landing. As he transitioned from the landing to ground roll, he applied pressure to the foot brakes, and the airplane swerved and departed the runway. The left wing made contact with the ground, and was substantially damaged along with the aft fuselage structure. The pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation.